Integrated photoelectrochemical-photovoltaic system with a dichroic spectral splitting for solar hydrogen production

The transition to sustainable energy requires efficient methods to convert solar energy into storable fuels. Photoelectrochemical (PEC)water splitting produces hydrogen from sunlight; however, it requires an external bias to proceed. A practical solution is the integration of PEC with photovoltaic (PV) cells in tandem systems, where the PV provides the necessary bias. This thesis investigates a PEC–PV tandem system assisted by a dichroic filter. The filter splits the solar spectrum: short-wavelength light is transmitted to the PEC cell, while long-wavelength light is reflected to the PV cell. This approach enables more efficient spectral use than stacked tandem devices, mitigating current mismatch and coupling losses. The dichroic filter was experimentally characterized, revealing deviations from ideal high-pass behavior. Mo:BiVO4 photoanodes were characterized by XRD and photoelectrochemical measurements. A commercial silicon PV cell was used and characterized. Photocurrents were measured under AM 1.5G illumination and compared with values calculated from IPCE data. Simulations evaluated configurations with idealized and optimized components, varying PV cell numbers, and different filter cutoff wavelengths. Moreover, the analysis quantifies how non-idealities of the dichroic filter reduce performance, and howoptimized cutoffs and improved photoanodes enhance the overall efficiencies. The results demonstrate that an optimized PEC-PV tandem system with dichroic splitting integration achieves a total efficiency that could overcome the efficiency of the PV component alone, all while simultaneously producing hydrogen. This represents a more efficient system than using separate components, where the PV cell powers a commercial electrolyser. Overall, this work highlights optical spectrum management as a key strategy for advancing PEC–PV systems and scalable solar hydrogen technologies.